The spreading of salt or other ice-melting materials as well as traction improving materials is a requirement in many areas for maintaining roads and driveways during the winter months. Various types of spreader units have been developed for spreading granular dry, free flow materials. Many such spreader units have been designed for mounting on vehicles such as trucks, either on the receiver of smaller trucks, or in the bed of larger commercial trucks that are used in wintertime road and driveway maintenance.
Spreaders generally hold a supply of granular material such as sand, rock salt, flake (calcium chloride), and/or bagged ice melters for distribution over a surface. Spreaders may be mounted in or on a vehicle which may be driven over the surface to be treated. The material moves from a hopper to a motor-driven spinner that distributes the material to the surface over which the vehicle moves.
Because salt spreaders are not used year round, they are generally removably mounted on the receiver of a truck, or, in the case of larger spreaders, in the bed of trucks. In either event, spreaders have a discharge outlet at the bottom of the hopper through which the particulate material, such as salt or sand, falls onto a spinning assembly or spinner. The spinner that is rotated by a drive assembly including an electric or hydraulic motor that causes the spinner to spread the particulate material discharged from the hopper over a wide distribution area behind the truck. The speed of the spinner may typically be varied to control the size of the area over which the particulate material is distributed.
In V-box spreaders and tail gate spreaders, the need for varying motor speeds is essential for optimum material spreading capabilities. The motors that are regulated in speed range from spinner motors, auger motors, vibrator motors, drum drives, drag chain drives and wetting systems drives. As used herein, “wetting system” refers to a system for dispensing wetting solution onto anti-icing material so that, among other things, the material does not stick together and disperses in the manner desired. All of the above-mentioned motors, when varied in speed, maximize profits for the customer, while maintaining conservation on material usage and optimizing material effectiveness against ice and snow.
One issue however with varying speed on motors is that they typically lose performance when throttled back or run at low speeds. This has to do with the way the motors are regulated in speed. The net effect is that a customer cannot utilize the full rpm range of the spreader, and therefore limited in what the spreader can do, especially at low rpm settings. It is not uncommon for customers to run the spreader at full speed at all times mostly because of the spreader limitations.
Vibrators are used in spreaders of all sorts including, but not limited to, tail gate hopper spreaders and v-box auger/pintel chain spreaders. The purpose of the vibrator is to jar loose material from a bridged condition or stuck to the walls of the hopper so that the material falls down through the spreader and ultimately onto the spinner.
One problem that is encountered is where turning the vibrator “on” can have undesirable consequences to either spreader performance or to overall pattern output. The ability to turn the vibrator “on” and “off” at the right time is advantageous with respect to optimum spreader performance. This prevents the spreader from jamming up and tends to maximize the spreader pattern so there is no disruption in material dispersion. Further, it can be difficult to predict when to turn on and off the vibrator while spreading the material as the operator is typically facing forward while the material is being spread behind the operator. Thus, the operator is not always looking at the material exiting the hopper spreader to know whether or not the vibrator needs to be activated. Some materials can be over vibrated such that if too much vibration is provided, the materials will pack such that it will not flow out of the hopper. Thus, simply leaving the vibrator on at all times while operating the hopper spreader is not an ideal option.
Bridged material that becomes jammed in the spreader may lead to the material becoming oversaturated with wetting solution, or may lead to the wetting solution being dumped into the chute without any material being dispensed.
The present invention pertains to improvements in the state of the art with respect to hopper spreaders. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.